[Stenzel]

MIDI is great, and I am so thankful that they had the foresight to require a mandatory opto-coupler in the input to avoid ground loops of interconnected gear. Even today, very few devices have a comparable insulation in their USB connection.

[exabrial]

On my guitar pedalboard, I tried to be clever once and I hooked all of my digital pedals with a usb hub to a main connector. Horrible ground loops and digital noise was introduced. Does anyone make an electrically isolated usb hub?

[klodolph]

A bit harder for USB, because of the power it supplies. USB is also not connected in loops, where MIDI will form loops with audio connections.